The present invention relates to an impact tool for a power driven impact hammer which is used to break hard objects such as rocks. The impact tool includes a high pressure water blasting system for directing pressurized fluid upon the object to be broken which cooperates with the impact tool in breaking up the object.
Impact tools are used in mining, quarrying, construction and demolition work to break apart hard objects such as large stones and blocks of aggregate. Impact tools are used in conjunction with hydraulic hammers that may be secured to an excavator boom. The hydraulic hammers include a piston which repeatedly exerts an impact, or shock, upon and through the impact tool. The impact tool is normally retained in a socket, or tool holder, which comprises part of the hammer.
Impact tools used in such hydraulic hammers are normally solid, blunt or pointed chisel tools made from tool steel. The impact tools are known to range from three to six inches in diameter and are designed to withstand impacts in the range of 500 to 5000 foot pounds. In operation, the impact tools are generally positioned against the object to be broken and the hydraulic hammer exerts an impact force upon the opposite end of the impact tool.
Impact tools are subject to wear and require replacement after several hundred hours of operation. The working end of the impact tool can become severely deformed over time. Impact tools are expensive and efforts have been made at extending tool life. Such tools are known to deliver from 250 to 1300 blows per minute. Even though the impact tools are made of tool steel, continued repetition of the impact leads to deformation of the tools.
One objective of impact tools is the extension of tool life. Another objective of such tools is the improvement of productivity and faster object breakage.
In mining and other environments where flammable gases are a potential problem, it is important to minimize the possibility that a spark will be created by the impact tool.
Another problem is caused by the build-up of heat in the impact tool as a result of the repeated impacts applied through the tool. When a tool is hot, it is more readily deformed.
These objectives are achieved and problems are solved by the present invention as summarized below.